Sleeve valve-actuated carburetor for internal combustion engines

ABSTRACT

A sleeve valve-actuated carburetor for internal combustion engines including a damping arrangement comprising an oil-filled conduit on the sleeve valve, a piston and piston rod extending into the conduit and including a passageway communicating with an oil supply chamber. The arrangement further includes a bent capillary tube connecting the oil supply chamber and interior of the piston rod for predetermined oil return flow so as to provide controlled damping of the carburetor operation.

United States Patent [191 Zahr et al.

[ SLEEVE VALVE-ACTUATED CARBURETOR FOR INTERNAL COMBUSTION ENGINES.

[75] Inventors: Karl-Heinz Zahr, Neuss; Giinter Hiirtel, Rosellen, both of Germany [73] Assignee: Deutsche Vergaser Gesellschaft m.b.H. & Co. KG, Neuss, Germany [22] Filed: Dec. 1, 1972 [21] Appl. No.: 311,439

[30] Foreign Application Priority Data Dec. 29, 1971 Germany 2165305 [52] US. Cl 261/44 R [51] Int. Cl. F02m 9/06 [58] Field of Search 261/44 R [56] References Cited UNITED STATES PATENTS 3,456,929 7/1969 Lawrence 261/44 R [451 Apr. 16, 1974 FOREIGN PATENTS OR APPLICATIONS 830,265 2/1952 Germany 26l/44 R Primary ExaminerTim R. Miles Attorney, Agent, or Firm-Eric I-ll. Waters 4 Claims, 1 Drawing Figure SLEEVE VALVE-ACTUATED CARBURETOR FOR INTERNAL COMBUSTION ENGINES FIELD OF THE INVENTION The present invention relates to carburetors and, more particularly, to a sleeve valve-actuated carburetor for internal combustion engines.

Various carburetors include sleeve valves employed as choke or throttling elements, each being connected on one side with a pneumatically operated flexible member which divides the carburetor housing into a sealed control pressure chamber and into a second chamber vented to atmosphere, and wherein the control pressure chamber includes a return spring adapted to bias the sleeve valve into a normally closed position. The sleeve valve has a piston rod which includes an inlet tube extending into the pressure chamber, and which is slidably supported in a guide conduit mounted in a carburetor housing cover adapted to seal the control pressure chamber with respect to the surrounding atmosphere.

DISCUSSION OF THE PRIOR ART An auxiliary hydraulic damper is provided so as to prevent excessively large oscillations of the piston rod of the sleeve valve. For example, a damper utilized in connection wich a carburetor of this type is disclosed in German Petty Pat. No. 1,982,141. The damper consists of an inlet tube extending into the control pressure chamber, with the tube being mounted on the sleeve valve and filled with a damping fluid such as, for exam ple, oil. A damping piston extends into the oil-filled inlet tube, and includes a piston rod which is fastened to the closure member of a housing cover. The damping piston includes one or more axially extending throttling bores which are controlled by a non-return valve, so as to provide for the retardation and damping of the upward motion of the sleeve valve, whereas the downward motion thereof remains essentially unretarded.

During the operation of the prior art carburetor it has been determined that, in view of unavoidable leakage losses; the oil supply of the hydraulic dampers must be replenished at short time intervals. In order to minimize oil leakage losses it has been proposed, as disclosed in German Pat.No. 830,265, to provide a ring-shaped or annular collection channel between the outer wallof the v inlet tube and the superimposed guide conduit thereof, for collecting leakage oil during the course of carburetor operation, and which is then returned to the interior of the inlet tube through a suitable aperture. Although this installation reduces the amount of oil leakage, leakage still is not completely eliminated. Furthermore, the obtention of a constant or steady oil level for the damping installation has not been attained.

The leakage oil which is received-in the annular or ring-shaped passage can only flow back to the inlet tube when the air piston is completely or almost completely in its lowermost operative end position. During partially loaded and fully loaded drive operation the aperture provided therefore is closed. Consequently, during the coure of carburetor operation, more and more oil is collected in the ring-shaped passageway, inasmuch as the oil supply in the inlet tube is pressurized during the upward motion of the air piston and is thereby pressed through the annular gap between the relatively sliding components in the oil receiving groove. The oil level of the damping installation is thereby forced down, and damping disturbances become unavoidable.

The collected leakage oil in presently employed in stallations may, during tilting operation of the motor vehicle, as well as during acceleration and deceleration sequences, flow outwardly over the edge, and thus be lost. These particular drawbacks and disadvantages are completely avoided by the present invention. The in vention has as its basic object the provision of an installation which compensates for the leakage losses of hydraulic dampers, and concurrently reduces service requirements for the carburetor over extensive time intervals.

In accordance with German Published application No. 1,936,640 it has been proposed that the closure member of the housing cover include a supply chamber for damping liquids, in which the chamber is sealed off from the atmosphere, which has a bottom partition connected to the interior of the inlet tube above the piston by means of a calibrated aperture located in the supply chamber and a coaxial passageway in the piston rod, and at least one radially extending aperture positioned below the fluid level in the inlet tube and adapted to be filled thereby. The drawback of this construction lies in the cumbersome constructional height of the carburetor.

SUMMARY OF THE INVENTION The present invention permits a considerable reduction in the overall height of the carburetor installation, and concurrently allows an increase in the quantity of the damping liquid reserve. In connection therewith, it is emphasized that the carburetor of the described prior art construction includes, in addition to the closure member, an adjacent annularly shaped supply chamber for the damping liquid which is hermetically sealed to the atmosphere, and in which the air stream above the liquid level in the supply chamber is connected with the interior of the inlet conduit above the piston, by means ofa coaxial passageway in the piston rod and by at least one radially extending aperture in the inlet tubesituated below the liquid level therein. 1

In accordance with the invention, it is proposed that the damping liquid or oil supply chamber is connected with the coaxial passageway in the piston rod through a U-shaped bent connecting conduit formedof capillary fluid aspirative material having unequal arms or extensions, in which the shorter extension depends toward the lower surface or bottom of the liquid supply chamber and thelonger extension depends toward the lower end or bottom of the coaxial passageway in the piston rod. The U-shaped connecting conduit may be formed of aspiration effective fibrous material. Furthermore, other materials such as, for example, capillary tubes may be employed. The coaxial passageway in the piston rod includes, in its upper portion, a suitable radially extending venting aperture.

BRIEF DESCRIPTION OF THE DRAWING Reference may now be had to the accompanying single FIGURE of the drawing disclosing an exemplary embodiment of the invention, and illustrating a crosssectional view of a sleeve valve-actuated carburetor.

DETAILED DESCRIPTION Referring now in detail to the drawing, the carburetor includes a carburetor housing 1 having an air inlet conduit 2 of circular cross-section. and an air-fuel mixture outlet conduit 3 similarly circular in cross-section. Extending perpendicularly downwardly, a sleeve valve 4 projects into the carburetor housing. The diameter thereof corresponds at its minor width with both of the aforedescribed conduits 2 and 3. When the sleeve valve extends completely into the housing, the passage of air therethrough is practically completely cut off. Through predetermined lifting of the sleeve valve there is provided a more or less increased flow-through crosssection between the conduits.

Through the intermediary of a flange 5 and fastening screws 6, a pneumatic elastically deformable positioning member or membrane 7 is connected with the sleeve valve in a gas-tight manner, The radially outer membrane edge is clamped, also in a gas-tight relationship, between the carburetor housing 2 and an upper housing closure portion 8.

At its lower end the sleeve valve supports, by means of a set screw 9, a jet nozzle 10 which may be vertically adjusted, and which extends into a fuel supply conduit 11, the latter of which has formed, at its upper edge, an annularly-shaped outlet aperture 12 for the combustion fuel. The fuel supply conduit 11 extends downwardly and opens below the fuel level in a float chamber 13. The fuel level in the float chamber is maintained practically constant by a float l4 and a fuel inlet floatcontrolled needle valve 15. The fuel enters into the float chamber 13 through an inlet conduit 16 past valve in the direction of the arrow.

The sleeve valve 4, which is hollow, has an integrally formed upward extending tubular guide conduit 17 interiorly thereof utilized for a hydraulic damping installation. A piston 19 extends into the damping liquid or oil supply 18 located in the guide conduit 17, the piston 19 being connected to an upwardly extending hollow piston rod 20, which in turn is centrally fastened in a closure member 21 mounted as a closing screw in housing closure portion 8. Below the oil level, in conduit 17, a radially extending aperture 31 in the piston rod communicates with theinterior of the coaxial passageway in the piston rod 20. An oil supply container 27 is formed on the housing closure portion 8, so as to form an annularly-shaped liquid supply chamber 22, which in association with a gas-tight threaded closing cover 23 fastened to housing closure portion 8, is hermetically sealed with respect to the atmosphere. The air space above the damping liquid in the supply chamber 22 is communicated with a control pressure chamber 33 by means of a vent tube 32. The piston rod includes, in addition to the radially extending aperture 31 formed therein below the liquid level in conduit 17, in its upper portion a similar radially extending venting aperture communicating with the coaxial passageway.

The supply chamber 22 is connected with the coaxial passageway in the piston rod 20 through a U-shaped bent connecting conduit 28 formed ofa capillary fluidconducting material. The connecting conduit 28 preferably consists of a capillary tube having a 0.5 mm inner diameter and a l.5 mm outer diameter. It includes two depending arm portions of unequal lengths, in which the shorter arm extends towards the floor or bottom of the supply chamber 22 and the longer arm extends into and forward the bottom of the coaxial passageway in the piston rod 20.

The drawing illustrates the carburetor in its at rest position, in effect, at a time subsequent to the shutting off of the internal combustion engine (not shown). At that time the damping liquid or oil slowly flows out of the supply chamber 22 through the connecting conduit 28 back into the damping liquid supply 18. As soon as the level of liquid supply 18 reaches the upper rim of the guide conduit 17, the internal combustion engine, and concurrently the carburetor and the damping fluid, has been cooled to an extent whereby damping fluid cannot flow through the annular gap between the guide conduit 18 and the tubular support 34 for the conduits which is connected to the housing closure portion 8, since the viscosity of the fluid is then too high.

The damping liquid flows out of the supply chamber 22 until the liquid level in the supply chamber 22 and of the supply 18 are at equal levels, as shown in the chain-dotted line in the drawing.

When the internal combustion engine is set into operation, the sleeve valve 4 is actuated. The sleeve valve is lifted, in view of which the oil supply 18 is concurrently lifted to the level of venting aperture 30. Upon further elevation or lifting of the sleeve valve 4, the oil supply 18 is displaced and forced through the apertures 31 and 30 into the coaxial passageway of the piston rod 20 and from there back into the supply chamber 22. The foregoing presented the theoretical problem, that upon warming up of the carburetor the damping liquid tended to flow outwardly more and more over the upper rim of the guide tube 17. This, however, is not the case in actual practice, since from time to time the gas pedal is either completely or almost completely depressed so as to move the sleeve valve 4 into its uppermost or practically uppermost end position. This causes a sufficient quantity of damping liquid to be concurrently displaced, so that the remainder fails to reach the upper rim of the guide conduit 17.

The refilling of the displacedoil is effected entirely through the capillary conduit 28. This sequence may be considerably extended, and correlated with the actual oil losses. In view of the foregoing it need not be considered further in accordance with the single described oil displacement, that after a considerable number of hours. sufficient oil flows through so as to reach the upper rim of the guide conduit 17 and then flows through the annular gap.

A particular advantage of the present invention lies in that the function of the carburetor is not adversely affected through losses in damping effects. A replenishment of damping liquid or servicing of the oil installation need be, if at all, only required after extremely lengthy time intervals, in comparison to presently employed sleeve valve-actuated carburetors. The utilization of the present invention thus greatly enhances the operative reliability of the entire internal combustion engine installation.

The invention possesses the further advantage, that there is attained a harmonious and compact overall construction of the carburetor, having relatively low height and minimum spatial requirements. Only through an arrangement in accordance with the invention, the liquid level of the supplychamber may be correspondingly advantageously lowered.

While there has been shown what is considered to be the preferred embodiment of the invention, it will be obvious that modifications may be made which come within the scope of the disclosure of the specification.

What is claimed is:

l. Carburetor for internal combustion engines. comprising a carburetor housing; a sleeve valve forming a choke movably supported in said housing; pneumati cally-actuated separating means dividing said housing into a control pressure chamber and an atmospherically vented chamber, said sleeve valve being fastened to said separating means; resilient means in said control pressure chamber biasing said sleeve valve into normally valve-closed position; upwardly extending guide means formed on said sleeve valve having a quantity of a'damping liquid therein and projecting into said control pressure chamber; an upper housing closure portion sealing said control pressure chamber relative to the atmosphere and having a support sleeve adapted to slidingly encompass said guide tube means; a closing member fastened to said upper housing closure portion above said guide tube means; piston rod means being fastened to and depending from said closure member into and in coaxial relation with said guide tube means; a piston supported on the lower end of said piston rod means and extending below the level of said damping liquid in said guide tube means; a sealed annular damping liquid supply chamber being provided above said control pressure chamber at an elevation higher than the liquid level in said guide tube means; a coaxial bore being formed in and extending into said piston rod means; a throttling orifice communicating said control pressure chamber with the region above said liquid supply chamber: said coaxial bore communicating the space above said liquid supply chamber with the interior of said guide tube means through at least one radial aperture formed in said piston rod above said piston and below the damping liquid level in said guide tube means; an invertedU-shaped connecting conduit communicating said liquid supply chamber with said coaxial bore in said piston rod means, said connecting conduit being of capillary fluid-conductive material having two depending arms of unequal lengths, the shorter arm depending toward the bottom of said liquid supply chamber and the longer arm depending toward the bottom of said coaxial bore; and non-return means in cooperative association with said sleeve valve providing for the damping operation of said. carburetor.

2. A carburetor as claimed in claim 1, said connecting conduit being formed of fluid-aspirating fibrous material.

3. A carburetor as claimed in claim 1, said conduit comprising at least one capillary tube.

4. A carburetor as claimed in claim 1, comprising at least one venting orifice communicating with said coaxial bore being provided in the upper portion of said piston rod means a 

1. Carburetor for internal combustion engines, comprising a carburetor housing; a sleeve valve forming a choke movably supported in said housing; pneumatically-actuated separating means dividing said housing into a control pressure chamber and an atmospherically vented chamber, said sleeve valve being fastened to said separating means; resilient means in said control pressure chamber biasing said sleeve valve into normally valve-closed position; upwardly extending guide means formed on said sleeve valve having a quantity of a damping liquid therein and projecting into said control pressure chamber; an upper housing closure portion sealing said control pressure chamber relative to the atmosphere and having a support sleeve adapted to slidingly encompass said guide tube means; a closing member fastened to said upper housing closure portion above said guide tube means; piston rod means being fastened to and depending from said closure member into and in coaxial relation with said guide tube means; a piston supported on the lower end of said piston rod means and extending below the level of said damping liquid in said guide tube means; a sealed annular damping liquid supply chamber being provided above said control pressure chamber at an elevation higher than the liquid level in said guide tube means; a coaxial bore being formed in and extending into said piston rod means; a throttling orifice communicating said control pressure chamber with the region above said liquid supply chamBer; said coaxial bore communicating the space above said liquid supply chamber with the interior of said guide tube means through at least one radial aperture formed in said piston rod above said piston and below the damping liquid level in said guide tube means; an inverted U-shaped connecting conduit communicating said liquid supply chamber with said coaxial bore in said piston rod means, said connecting conduit being of capillary fluidconductive material having two depending arms of unequal lengths, the shorter arm depending toward the bottom of said liquid supply chamber and the longer arm depending toward the bottom of said coaxial bore; and non-return means in cooperative association with said sleeve valve providing for the damping operation of said carburetor.
 2. A carburetor as claimed in claim 1, said connecting conduit being formed of fluid-aspirating fibrous material.
 3. A carburetor as claimed in claim 1, said conduit comprising at least one capillary tube.
 4. A carburetor as claimed in claim 1, comprising at least one venting orifice communicating with said coaxial bore being provided in the upper portion of said piston rod means. 